Originally from Thailand, it is often called marcasite, also known as "Black Silver". White iron ore is made by using the characteristic that silver will turn black when it comes into contact with sulfur. It melts the mixture of silver and sulfur on silver jewelry by heating, and forms a covering layer in the glass state. The covering layer of Makasite is loose and black, which is in sharp contrast with the smoothness and silver of silver, and produces special visual effects. After special anti-aging treatment, marcasite jewelry not only does not change color for a long time, but also has a much higher surface hardness than ordinary silver. The unique texture and color make people feel the roughness and simplicity of this kind of jewelry.